Per-segment overrides
Style one caption differently from the rest without breaking the global look
Most of the time you want every caption to look the same. Once in a while you don't. A title card needs to be bigger. A name super needs a different color. A pull quote sits in the middle of frame instead of the bottom. The override system handles this without making you maintain two style sets.
Global vs Override
The Style tab and the Position tab both have a mode picker at the top: Global or Override.
Global edits apply to every segment. They also clear any per-segment overrides for the fields you change. Edit the global font size and any segment that had its own size override loses that override and falls back to the new global.
Override edits apply only to the segments you selected back on the Captions tab.
If you have segments selected on the Captions tab when you open Style or Position for the first time, the picker auto-flips into Override mode. So the most common workflow just works: select the title card row on the Captions tab, hit ⌘2, the tab is already in Override mode, change the size.
What a "field" means
Override is per field, not per panel. If you override the font size on segment 4, only the size is overridden. Color, outline, shadow, glow, position, all of those still come from Global. Edit the global color later and segment 4's color follows. It only diverges where you explicitly told it to.
This is why Reset asks what you want to reset. More on that next.
Reset behavior in each mode
The Reset button lives on the Style tab and the Position tab. It does different things depending on the mode you're in.
Global mode, Reset. Resets the global values (font, color, outline, shadow, glow on the Style tab; anchor and margins on the Position tab) to defaults across every segment. It also clears those fields from any per-segment overrides. Position resets don't touch Style and vice versa.
Override mode, Reset. Clears those fields from the selected segments only. The selected segments fall back to Global for whatever you cleared.
Both versions ask for confirmation. ⌘Z reverses the reset.
A working pattern
Build the global look first. Get the font, color, outline, and bottom-anchor position the way you want them across the whole video. Then go through and override the few segments that need to be different. Title at the top of frame, name super in a different color, the closing tag in a bigger size.
When you ship the next video and want a slightly different global look, change Global. The overrides on the special segments stay where you put them, because they're on different fields. The global tweak ripples through everything else.
Animation doesn't have overrides yet. If you need a single segment to animate differently, that's a real limitation today. We'd rather build it right than ship a version we'd tear out later.